Re: Me against the meme

From: Derek Gatherer (d.gatherer@vir.gla.ac.uk)
Date: Mon 14 Nov 2005 - 14:52:33 GMT

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    At 19:05 11/11/2005, Dace wrote:

    >causation based on contact mechanics. This attitude cropped up again in the
    >news recently when it was reported that a small number of Arabidopsis
    >thaliana plants had mysteriously reverted to the genes of its grandparents
    >in place of the mutant genes of its parents. All the mutations of their
    >parents had been repaired, as if they'd been descended directly from their
    >wildtype grandparents. Researchers were baffled as to how the plants knew
    >what the pre-mutant genetic sequences were. They then concluded that there
    >must be a complete copy of the plant's genes contained in its RNA, and it
    >was from this copy that the numerous, disparate mutations in its genome were
    >repaired. Now, there's no evidence that RNA contains any genes at all, much
    >less a complete set of them. Whether or not the researchers are correct,
    >they're making an awfully big assumption. Both Scientific American and
    >Science reported it as a done deal: there must be another copy of the genome
    >in RNA. No evidence, just blind allegiance to reductionistic metaphysics.
    >Of course, it's just as likely that the wildtype reversion is based on
    >holistic memory, but the cult of reductionism doesn't allow for this
    >possibility.

    I think you must be referring to the papers in Nature (March and Sept)

    http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15785770&query_hl=11

    was the first one. Actually the reversions were in a pair of loci, not the whole genome. There are a couple of possible explanations, eg:

    gene conversion:

    http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16136081 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16136082

    or toxic mutator and selection:

    http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16267378&query_hl=11

    The back-transcription from RNA theory and the 2 alternative theories are all perfectly plausible in terms of known biochemical mechanisms. It's just a question of which, if any, is the correct one - the answer to which will be obtained by standard laboratory investigation. No need for any theories requiring us to abandon the world as we currently know it.

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